Question

The side of an equilateral triangle AABC is 5cm. Find the length of the side of another
equilateral triangle PQR whose area is four times area of AABC.
(A) 5cm
(B) 8cm
(C) 10cm
(D) 12cm​

Answer 1

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Asked on December 20, 2019 by

Arpita Nandy

One side of an equilateral triangle measures 8 cm. Find its area using Heron's formula. What is its altitude

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ANSWER

According to the Heron's formula, Area (A) of the triangle having sides a,b,c units is

A=

s(s−a)(s−b)(s−c)

where

s=

2

a+b+c

For the given triangle,

a=b=c=8cm

s=

2

8+8+8

=12

A=

12(12−8)(12−8)(12−8)

A=

3×4×4

3

=4×4

3

=16

3

Area of the triangle =

2

1

×base×altitude=16

3

2

1

×8× altitude=16

3

Altitude =

4

16

3

=4

3